Cu-doped MIL-101(Fe) with unsaturated metal sites activate peroxymonosulfate for efficient degradation of ciprofloxacin: Optimization, mechanism, and toxicity assessment

Abstract

The efficient exposure of active sites of MOF materials for the catalytic reaction is challenging. In this study, we report the successful synthesis of a novel Fenton-like catalyst, 0.2Cu/MIL-101(Fe)-300, utilizing a modified solvothermal method followed by thermal activation. 91.7 % of CIP was degraded in 30 min by dosing 0.2Cu/MIL-101(Fe)-300 (0.05 g/L) and PMS (0.1 mM) at pH 7, and the kinetic constant was 15.2 times higher than that in MIL-101(Fe)/PMS system. A systematic investigation was conducted to evaluate the influence of catalyst dosage, PMS concentration, initial pH, and the presence of coexisting anions on the degradation of CIP, aiming to optimize the degradation process. The quenching tests and EPR analysis revealed that the oxidation reaction involved multiple ROS, including SO₄^•−, •OH, O₂^•−, and ¹O₂, with SO₄^•− and •OH identified as the primary ROS responsible for the degradation of CIP. Furthermore, potential degradation pathways for CIP were outlined, and the toxicity of the resulting intermediates was evaluated. This work provides a novel approach for creating highly effective, durable, and non-toxic Fenton-like catalysts to attain outstanding environmental restoration efficacy across a wide pH range.